Fungi, insects and bacteria look set to pose an increasing threat to global food production in years to come,new researchreveals. As temperatures rise, crop-destroying pests and diseases are spreading from the tropics toward the poles at a rate of nearly three kilometres per year.

The rising problem of pests in some of the world’s most productive farmland presents a real threat to global food security, as climate change makes higher latitudes like the US and Europe more hospitable to pests that wouldn’t otherwise survive.

How bad is the pest problem?

For farmers worldwide, pests are already a serious problem. They are responsible for the loss of between 10 and 16 per cent of all crops during production, and result in further losses after harvest i.e. due to infestations in food stores.

From microscopic fungi, bacteria and viruses to insects and other animals, there are numerous different species which affect everyday staples like cereals, potatoes, fruit and vegetables. These pests have evolved to breed quickly and disperse easily, allowing them to move readily to find new hosts.

Given the right amount of warmth and moisture, these pests thrive and grow. The new study suggests that changes to these aspects of the climate are allowing pests to become established in previously unsuitable regions.

The UK government identified increasing pest numbers as a potential problem in its 2012 assessment of the climate risks facing the country. At the time, there wasn’t enough evidence to confidently say how pests would affect farmers’ yields, but studies like this might start to change that.

Poleward shift

Using records dating back to the 1960s, researchers from the University of Exeter & the University of Oxford spotted that a wide range of pests were spreading from the tropics towards the poles. While international trade in food helps spread pests further and faster than other species, it’s changes in the climate which allow the pests to take hold, say the authors.

Their study shows pests’ poleward shift is happening at a rate of about 2.7 kilometres per year – give or take a bit. By our maths, that’s about 135 kilometres over the last 50 years, or 27 kilometres per decade.Compared to how fast other wild species are moving towards the poles – about 18 kilometres per decade – it’s clear pests are spreading much quicker.

The pace of pest spread is not surprising though – in fact it’s pretty much exactly what scientists expect, given the temperature rise earth has experienced in recent decades. This makes the authors confident that as a result of climate change, pests could compromise crop harvests worldwide, including high latitude regions like Europe and the US where agricultural productivity per unit land area is highest.

So climate change is bad news for crops?

If this research is correct, the indirect impacts of climate change could have considerable consequences for global food production. The authors warn:

“If climate change [makes] it easier for crop-destroying organisms to spread, renewed efforts to monitor the occurrence of pests and diseases and control their transport will be critical in controlling this growing threat to global food security.”

But as the paper also acknowledges, future global food security depends on a number of physical and socio-economic factors i.e. population growth. Looking at just one aspect of how climate change might affect crops can be misleading, as research published last week showed.

At the moment, it looks like growing crops could get a lot tougher in the future. Whether technological advances can keep pace with climate change remains to be seen.